Custom orthodontic appliance forming method and apparatus

ABSTRACT

A system ( 10 ) and method by which an orthodontic appliance ( 25 ) is automatically designed and manufactured from digital lower jaw and tooth shape data of a patient provides for the scanning of the mouth of a patient ( 12 ), preferably from a model ( 20 ) of the patient&#39;s mouth, to produce a three-dimensional digitized model ( 26 ) of the shapes of the patient&#39;s teeth and their positions in the patient&#39;s mouth. Then a computer ( 30 ) calculates the post-treatment positions of the teeth and produces three-dimensional images of the teeth, individually and in their calculated positions. An interactive computer link between the doctor&#39;s office ( 11 ) and the appliance manufacturing facility ( 13 ) allows an orthodontist ( 14 ) to control the patient&#39;s archform and to modify the suggested computer-determined positions and orientations of the teeth in six degrees of freedom, and to experiment with new positions, extractions, over-corrections and other variations, with the computer recalculating the tooth positions with high precision for the approval of the orthodontist. The appliance is automatically designed according to the final design, which also can be interactively modified and approved by the orthodontist, with the computer recalculating the effects on the treatment as a result of the doctor&#39;s changes. Brackets ( 81 ) are fabricated as an integrated set, either by cutting slots therein or by building the brackets in layers by, for example, stereo lithography. Three-dimensional custom jigs ( 87 ) are automatically made to exactly position the brackets on a patient&#39;s teeth.

This application is a continuation of International Patent ApplicationNo. PCT/US00/35558, filed Dec. 29, 2000. which is an InternationalApplication of U.S. Provisional Patent Application Ser. No. 60/173,890,filed Dec. 29, 1999. both of which arc hereby expressly incorporatedherein by reference in their entirety.

This application is related to U.S. patent application Ser. No.09/431,466, filed Nov. 1, 1999, which is a continuation of U.S. patentapplication Ser. No. 08/960,908, filed Oct. 30, 1997, now U.S. Pat. No.6,015,289, which is a continuation of U.S. patent application Ser. No.08/456,666, filed Jun. 2, 1995, now U.S. Pat. No. 5,683,243, which is adivisional of the following U.S. patent applications, each of which wasfiled on Nov. 9, 1992:

-   -   Ser. No.: 07/973,973 entitled Method of Forming Custom        Orthodontic Appliance, now U.S. Pat. No. 5,431,562,    -   Ser. No.: 07/973,965 entitled Custom Orthodontic Brackets and        Bracket forming Method and Apparatus, now U.S. Pat. No.        5,454,717,    -   Ser. No. 07/973,947 entitled Custom Orthodontic Archwire forming        Method and Apparatus, now U.S. Pat. No. 5,447,432,    -   Ser. No.: 07/973,844 entitled Method and Apparatus for Forming        Jigs for Custom Placement of Orthodontic Appliances on Teeth and        Jigs Formed Therewith, now U.S. Pat. No. 5,368,478;        and is also related to U.S. Pat. Nos. Re 35,169; 5,139,419;        5,395,238 and 5,518,397.

All of the above related patents and applications are assigned to theassignee of the present application, and all are hereby expresslyincorporated by reference herein.

FIELD OF INVENTION

The present invention relates to the design, manufacture and use oforthodontic appliances for the straightening of teeth, and moreparticularly, to the automated design, manufacture and use of customorthodontic appliances based on individual patient anatomy and to thetreatment of patients therewith.

BACKGROUND OF THE INVENTION

The orthodontic treatment of patients has as its fundamental objectivethe repositioning or realignment of the teeth of a patient in thepatient's mouth to positions where they function optimally together andoccupy relative locations and orientations that define opposed andcooperating smooth archforms. A common technique for achieving thisobjective is to position orthodontic brackets on a patient's teeth suchthat archwire slots in the brackets will align when the teeth are intheir corrected positions, and to place an elastic archwire in the slotsthat urges the teeth toward their corrected positions as the wire tendsto straighten. In an ideal situation, a perfectly positioned, perfectlydesigned appliance used in this manner will theoretically move the teethto their intended corrected positions without intervention in the formof “wire bending” by the orthodontist. With most appliances made toapply to standard statistically average dental anatomy, the ideal isseldom, if ever, realized.

The patents identified above describe the design, manufacture and use ofcustom orthodontic appliances designed and built with the aid of acomputer. With such automated appliance design and manufacturingsystems, the collection of data of the shapes of the patient's dentalanatomy, the processing of the collected data to create an appliance inaccordance with the treatment prescribed by an orthodontist, the preciseand economic manufacture of the custom orthodontic appliance, and theefficient and accurate placement of the appliance on a patient's teethare important.

Accordingly, there is a great need in orthodontics for a practical,reliable and efficient custom appliance automated design andmanufacturing system, and method of providing custom appliances andtreating patients therewith.

SUMMARY OF THE INVENTION

A primary objective of the present invention is to provide a practical,reliable and efficient custom appliance designing and manufacturingsystem and to provide a method of designing custom orthodonticappliances and treating patients therewith. A more particular objectiveof the invention is to provide for improved automation in orthodonticappliance design and manufacture, especially for custom orthodonticappliances.

A further objective of the present invention is to provide customorthodontic appliance design and manufacturing involving an efficientand effective distribution of functions and decision making among theorthodontist, the appliance manufacturer and the specially programmedcomputer. Another objective of the present invention is to apportiontasks involved in the design and manufacture of custom appliances mostefficiently between orthodontist and appliance manufacturing facility inaccordance with the scale and other particulars of the individualpractitioner operation, giving the orthodontist optimum control over thefinal archform and of the treatment process, while increasing theaccuracy of treatment and the efficiency of use of the orthodontist'stime and eliminating guesswork and sources of error.

Another objective of the present invention is to improve the practice oforthodontics by aiding the practitioner in achieving optimal treatmentof patients and in more accurately determining and precisely achievingthe placement of a patient's teeth, and particularly in enabling theperformance of an orthodontic appliance and the results of orthodontictreatment to more closely conform to the appliance design and treatmentplan.

An additional objective of the present invention is to provide morecomplete three-dimensional control in the design, manufacture and use ofan orthodontic appliance and in the movement of the patients teeth inorthodontic treatment.

According to principles of the present invention, a system and methodfor designing and making a custom orthodontic appliance are provided. Inthe system and method, an orthodontist provides a record ofthree-dimensional dental anatomical information from the patient's mouthat the orthodontist's office or clinic and transmits the record to anappliance design facility or lab. From the digital model, a customorthodontic appliance is designed by the lab on a computer in accordancewith preprogrammed criteria and a prescription from the orthodontist. Acustom orthodontic appliance is made from the computer generated design.

The record may be in the form of a physical model, usually in the formof a cast replica of the patients upper and lower jaws, with the teethin their pretreatment positions, made from an impression or mold of thepatient's mouth made by the orthodontist. Where the physical model istransmitted to the lab, the lab scans the model with a laser or otheroptical scanner, or other type of scanner, preferably a non-contactscanner. The scanning produces a three-dimensional digital model of thepatients mouth, including the shapes of the teeth and jaw of the patientand the positions of the teeth in the patient's mouth. Alternatively,the scanning of the model can be carried out by the orthodontist at theorthodontist's office or digital information can be derived from a fulloral scan directly of the patient's mouth, and the digital scannedinformation then transmitted to a lab remote from the office.

The scanning is preferably carried out with a laser scanner, first in alow resolution mode which locates the model on a workpiece support andprovides a basis for identifying the portion of the scanned image thatis of interest and identifying the various teeth, boundaries and otheranatomical features to be digitized. Then, in high resolution mode, thefeatures that were identified in the low resolution mode are scanned toproduce high resolution, three-dimensional image files of the shapes ofeach of the teeth. An operator at the lab supervises the identificationof landmarks and other properties and features of the scanned data. Thelandmarks include all of the cusps and incisal tips of the teeth, thecentral grooves and marginal ridges of the teeth, and gingival points onthe facial and lingual sides of the teeth, as well as other landmarksdescribed below.

The determination of tooth finish or posttreatment positions is carriedout interactively with the orthodontist by communication with a computerat the appliance design facility. The computer first calculates asuggested posttreatment setup of the teeth, which the orthodontist canmodify and have recalculated until the final treatment positions of theteeth have been approved by the orthodontist. This allows theorthodontist to move any of the teeth in six degrees of freedom: bytorque, tip or rotation angles, mesial-distally, labial-lingually orocclusal-gingivally. The orthodontist can thereby test archforms, forexample with and without extractions and with or withoutover-correction, and to view the posttreatment results on a computerscreen, with the teeth as three-dimensional solid objects.

After the final tooth positions are decided upon, then a customappliance is designed by the computer in accordance with the approvedtooth finish position or posttreatment setup of the teeth. As with thetooth setup, the design of the appliance is interactively adjusted,tested and approved by the orthodontist. Once the appliance design isapproved, the appliance is made by computer controlled equipment inaccordance with the design.

The high resolution, three-dimensional data of the shapes of the teethare used in the calculations of tooth finish positions and in the designof a custom orthodontic appliance to move the teeth to the calculatedfinish positions and to fit the appliance to the surfaces of thepatient's teeth. The data may be used to design the shapes of the basesof orthodontic brackets to precisely conform to the surfaces of theteeth at the points thereon at which the brackets are to be bonded. Thethree-dimensional data is particularly beneficial when used to designthe shapes of jigs to precisely conform to the surfaces of the teeth touniquely position an appliance on the teeth, such as locating bracketsat calculated ideal positions on the teeth for bonding thereto. Suchjigs include any structure having a negative image of a tooth surfacethat functions to locate on one or more teeth an orthodontic applianceor other structure that is added to assist in the orthodontic treatmentof a patient's teeth. Such jigs are beneficial in positioning fullycustom designed brackets and other appliances as well as in positioningsemi-custom or standard brackets at their ideal positions on a patient'steeth, or in locating any other structure for bonding to a tooth or tootherwise position on patient's teeth.

The calculations of the finish positions of the teeth locate the crownlong axes of the teeth in three dimensions with the torque, tip androtation angles of the axes and planes containing the axes preciselydetermined as well as the x-y-z positions of the axes.

Manufacture of custom appliances includes the making of a generallyarch-shaped appliance to move the teeth to their calculated finish orposttreatment positions on calculated archforms established in aninteractive process between a computer and an orthodontist. Theappliance type preferably is a straight wire orthodontic brace systemthat includes a set of orthodontic brackets bonded one to each of aplurality of a patient's teeth, usually a set of buccal tubes secured bybands or bonding to the most distal of the patient's teeth, and a set ofarchwires ligated in slots in the brackets. Retainers, positioners andother arcuate or generally arch-shaped appliances may be similarlydesigned by the system described herein, as well as other forms oforthodontic appliances.

The manufacture of archwires is accomplished by operating computercontrolled equipment to shape one or more archwires of the customdesigned appliance. Archwires may be so formed by feeding and bendingwire from continuous wire stock, which is useful for wires of steel andsimilarly formable metals, using wire bending machinery controlled inaccordance with a calculated archwire shape. Wires may also be formed bymilling, cutting or otherwise imposing the calculated archwire curve onor in a plate or form, into which a wire is placed and annealed orotherwise heat treated, which is particularly useful for makingarchwires of high elasticity metals such as titanium or titaniumcontaining alloys. Other types of orthodontic appliances or applianceaccessories, such as brackets, retainers, positioners, or positioningjigs may be made by this process.

Orthodontic brackets of a set required to treat a patient may be formedby cutting slots in bracket bodies, each welded to a bracket base, allof which bases of the set are formed of a single sheet of metal bracketbase material. The bases may be custom formed to curve to conform to thesurfaces of the patient's teeth or may be curved to the standardcurvatures of statistically average teeth. Whether the bases are customor standard in curvature, slots may be cut into the brackets to thein-out depth, rotation, tip and torque that are custom to the idealappliance for the patient. The single sheet of metal serves as awork-holder to hold all of the brackets of the set in predeterminedpositions during the slot cutting procedure.

Orthodontic brackets as well as other orthodontic appliances andappliance components may alternatively be formed by deposition ofmaterial in layers, shaped according to the cross sections of theappliance according to its calculated geometry. The materials sodeposited can be made up of different materials that are differentiallydeposited to define the cross section shapes, may be one or more typesof materials that are selectively activated, cured or hardened, such asby exposure to light, heat or chemicals, and with the selectivity beingcarried out in accordance with the calculated appliance shape dataproduced in the custom appliance designing process. In forming bracketsusing the layer deposition process, one or more intermediate objects maybe formed from which an appliance having a surface shaped to matinglyconform to the surface of the crown of a tooth may be formed. Suchintermediate objects may be in the form of a mold or a pattern for themaking of a mold.

For example, different waxes may be deposited, for example, by a jetprinting process to build up the bracket shape as a stack of layersproducing a three-dimensional wax pattern, which then can be used toform a mold to produce a custom bracket by an investment castingprocess. Materials out of which the brackets are to be ultimately mademay also be deposited by a dot printing process, for example, depositingmetal and binder mixtures that may be of different compositions todefine the shape of the appliance being produced. Alternatively,homogeneous materials may be deposited but selectively cured, usinglaser energy or some other high resolution selective process. Suchprocesses may produce a multi-layered object of material that willwithstand heat or a solvent used to remove the material surrounding theportion of the material defining the appliance or appliance part,leaving an object that becomes the bracket, for example, or becomes apattern for a mold to form the appliance or appliance part.

Jigs for the positioning of one or more brackets or other appliances orappliance parts are formed by any of several possible processes, forexample, that produce a cavity shaped to precisely conform to theocclusal surface of the crown of the one of the patient's teeth on whichone or more appliances are to be positioned for bonding. The applianceor appliances to be bonded are configured in cooperation with the jig toattach to the jig so that each appliance will be located at one and onlyone position on the surface of the tooth when the jig is fitted in itsunique position and orientation on the occlusal surface of the tooth.Preferably, when a set of brackets and bracket positioning jigs isprovided according to the system and method described herein, thebrackets and jigs are pre-attached to each other in predeterminedrelative positions and orientations at the appliance manufacturingfacility so that the jigs need be removed only after the orthodontisthas bonded the brackets to the teeth of the patient for which theappliance is designed.

These and other objectives and advantages of the present invention willbe more readily apparent from the following detailed description of thedrawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating one embodiment of a customorthodontic appliance designing and manufacturing system according toone embodiment of the present invention.

FIG. 2 is a flowchart of one embodiment of the process of the presentinvention perforated with the system of FIG. 1.

FIG. 3 is a perspective diagram of a three-dimensional graphics imagingscanner of the system of FIG. 1.

FIG. 3A is a representation of the display produced by the computer ofthe scanner of FIG. 3 illustrating three views of a low resolutionscanned image of a model of a patient's lower dental arch

FIG. 3B is a computer display of perspective representation highresolution data scanned by the scanner of FIG. 3 from a model of apatient's lower dental arch.

FIG. 4 is an illustration of a display of the appliance facilitycomputer of the system of FIG. 1 displaying an initial setup screen.

FIG. 4A is a diagram of a portion of the setup screen of FIG. 4:

FIG. 4B is an illustration of a display of the appliance facilitycomputer of the system of FIG. 1. similar to FIG. 4. displaying another,setup screen.

FIG. 4C is an illustration of a selected display window of the screen ofFIG. 4B showing a tooth cross section in a crown long axis plane.

FIG. 5 is a display of the appliance facility computer displaying aperspective view of the patient's teeth, in high resolution,three-dimensional solid images in their relative positions prior totreatment.

FIG. 5A is another setup screen display of the appliance facilitycomputer displaying various view windows showing the teeth of thepatient in their relative pretreatment positions of FIG. 5A.

FIG. 5B is a display of the appliance facility computer, similar to FIG.5, displaying a perspective view of the patient's teeth in highresolution, three-dimensional solid images, in calculated proposedrelative posttreatment positions.

FIG. 5C is a display of the appliance facility computer, similar to FIG.5A, displaying various view windows showing the teeth of the patient inthe relative posttreatment positions of FIG. 5B.

FIG. 5D is a display of the appliance facility computer displaying, aperspective view of the mandibular teeth of a patient in theposttreatment positions of FIGS. 5B and 5C shown in solidthree-dimensional images with simplified vector representationssuper-imposed thereon.

FIG. 5E is a display of the appliance facility computer, similar to FIG.5A, displaying various views of the patient's teeth, in high resolution,three-dimensional solid images, in relative posttreatment positions witha custom designed appliance thereon.

FIG. 5F is a display of the appliance facility computer with a selectedscreen window enlarged and illustrating a tooth cross section with acustom designed bracket of the appliance of FIG. 5E positioned thereon,and illustrating a hybrid perspective view of simplified vector imagesand solid three-dimensional images of the mandibular teeth of thepatient in the posttreatment positions with the custom designedappliance thereon.

FIG. 5G is a display of the appliance facility computer illustrating aselected screen window showing an alternative hybrid perspective view tothat of FIG. 5F of simplified vector images and solid three-dimensionalimages of the mandibular teeth of the patient in the posttreatmentpositions with the custom designed appliance thereon.

FIG. 6 is a disassembled perspective view of a custom designed bracketand the corresponding custom designed bracket placement jig thereforeillustrated in relation to the tooth on which the bracket is to beplaced.

FIG. 6A is a perspective view of a set of custom jigs formed accordingto one embodiment of the system of FIG. 1.

FIG. 6B is a perspective diagram illustrating the milling of a customjig of FIG. 6A.

FIG. 7 is a sequential perspective diagram of a custom archwire formingsystem according to one embodiment of the system of FIG. 1.

FIGS. 8A-8D are sequential diagrams of a custom bracket forming systemaccording to one embodiment of the system of FIG. 1.

FIGS. 9A-9C are perspective diagrams of a custom bracket forming systemaccording to another embodiment of the system of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

One embodiment of a custom orthodontic appliance manufacturing system 10according to principles of the present invention is diagrammaticallyillustrated in FIG. 1. A process by which the system 10 may operate isillustrated in the chart of FIG. 2. The system 10 may be distributedamong a plurality of locations, preferably between two locations, whichinclude an orthodontist's office 11 and an orthodontic appliancedesigning and manufacturing facility or lab 13. The actions and decisionmaking in the operation of the system 10 is distributed among threepaths, including (1) the orthodontist 14 located at the office 11, (2)data gathering and processing equipment 30,33 and appliancemanufacturing equipment 38, located mostly at the lab 13 but some ofwhich may be located at the office 11, and (3) the lab operator 28located at the facility 13. These three paths are represented by thethree columns in FIG. 2, wherein the steps performed by the orthodontistare illustrated at the left, the steps performed by the computers andother equipment are illustrated in the center, and the steps performedby operators at the facility 13 are illustrated at the right. The dashedlines represent interactions, including exchanges of information,between the paths.

At the office 11, orthodontic treatment of a patient 12 is undertaken byan orthodontist 14, at the office 11, who makes a diagnosis 15, which isreduced in form to one of several data records 16. The records 16 aregenerated as part of the case information necessary to determine thepatient's condition, prescribe the appropriate treatment, and specifythe type of orthodontic appliance to implement the treatment of thepatient 12. The case information data records 16 include informationidentifying the patient 12, anatomical data of dental and related shapesfrom the mouth 18 of the patient 12, and preferably other backgroundinformation 19, such as racial and genetic information that has arelation to the dental anatomical characteristics of the patient thatcan be useful in selecting or designing treatment and the types ofappliances to be used in the treatment.

Examination of the patient 12 by the orthodontist 14 involves thetraditional application of the skill, knowledge and expertise of theorthodontist 14, and results in the creation of a detailed anatomicalrecord of the shape and initial malocclused locations of the teeth inthe patient's mouth as well as the jaw structure of the patient 12. Thisdetailed anatomical record may be in the form of a physicalthree-dimensional model 20 of the patient's mouth 18. Such a model 20 istypically a cast formed in a mold impression, made by the orthodontist14, of materials such as alginate for example, of the patient's mouth18, according to traditional procedures known to orthodontists. Themodel 20 is usually made of plaster and includes a mandibular casting ormodel 21 of the patient's lower jaw or mandible 22 and a maxillary model23 of the patient's upper jaw or maxilla 24, each replicating the shapesof the patient's teeth in their relative pretreatment positions in therespective lower and upper jaws.

The orthodontist 14 determines the general type of orthodontic appliancewith which the patient 12 is to be treated, as well as certainparameters of such an appliance. In the system 10, the appliance is acustom orthodontic appliance 25 of a generally arcuate or arch-shapedshape that the orthodontist 14 installs on the patient's teeth. Toinitiate production of the appliance 25, the orthodontist 14 transmitsthe physical model 20 to the appliance designing and manufacturingfacility 13 along with the other data records 16, including aprescription 27 wherein the orthodontist sets forth a treatment plan tobe applied to the patient and specifies a result to be achieved by thetreatment. As an alternative to transmitting a physical model 20 to thefacility 13, a digital model 26 may be generated at the orthodontist'soffice 11, either directly from the patient's mouth 18 without the useof a physical model 20, or from the physical model 20, so that thedigital model 26 may be transmitted to the appliance manufacturingfacility 13.

The prescription 27 may include a specification of techniques that areto be included in the treatment and a designation of an orthodonticappliance to be employed. Historically, such a prescription 27 is not sodetailed as to include precise mathematical arrangements or movements ofthe teeth that the treatment will produce, but may include treatmentgoals, including some expressed in numerical values representing thearrangement of the teeth that is sought.

The facility 13 is provided with one or more trained operators 28. Anoperator 28 supervises the input of data into the computer 30, includingthe data of the digitized model 26 and also data of treatment plan andappliance design decisions or parameters. This data may be input intothe input computer 30 a or another computer 30 b specifically dedicatedto the design of the custom appliance 25. An operator 28 may also addinput to or control operation of appliance manufacturing equipment 38controlled by computer 30, such as by computer 30 b or by anothercomputer or machine controller 30 c to manufacture the appliance 25.Where the inputting, design and manufacture are performed at theappliance facility 13, the computers 30 a, 30 b and 30 c may be the samecomputer 30 or separate computers or controllers that are linked to eachother or otherwise exchange data.

Where the physical model 20 itself is transmitted to the facility 13,the operators 28 operating scanning equipment 33 to generate digitalinformation 26 in the form of a three-dimensional digital model of thepatient's teeth while in their pretreatment positions in the patient'smouth. Alternatively, the digital model 26 is received by the operator28 from the orthodontist 14. The digital model 26 produced from thephysical model 20 or received directly from the orthodontist 14 is inputinto a computer 30 a. The input computer 30 a is particularly useful tomanage the generation of the digital information 26 by controlling thescanning of the physical model 20, for example, with a three-dimensionallaser scanner 33, to produce the 3-D digital model 26. The inputcomputer 30 a utilizes interaction from the operator 28 to efficientlyguide the scanner 33 in the scanning of areas on the surface of theteeth and in the selection of particularly useful orthodontic parametersfrom graphic images produced by the scanner 33 on a screen 35 of adisplay connected to the inputting computer 30. The scanner 33 acquires3-D data from the three-dimensional surfaces of the physical model 20and inputs the acquired data to the computer 30 a, which produces thedigitized anatomical information or digital model 26 in machine readableform for analysis by the appliance design computer 30 b. The operator 28inputs information used to simplify the 3-D data to define the teeth andother dental anatomy of the patient in terms of landmarks or othercriteria that are useful in the setup of the case or the design of theocclusion that is the objective of the treatment plan. Algorithms mayalso be used to determine these landmarks and other criteria with littleor no operator interaction.

The scanner 33 may include one or more video cameras, mechanical probes,laser or other optical scanners, ultrasonic scanners, moire imagescanners or other forms of imaging or measurement hardware that alone,or in combination with other such components, produce athree-dimensional digital model of the surface of the patient's teethand mouth tissue defining the shape of the patient's jaw. While a laserscanner 33 is illustrated, other types of scanners, preferablynon-contact scanners, may be used, and as technology progresses, manytypes of such scanners are becoming available, such as digital opticalscanners that use coded pulsed white light.

The data of the 3-D digital model 26 is processed, along with other datafrom the orthodontist 14, and interactive selections made by theoperator 28 and/or the orthodontist 14 to determine tooth finish ortreatment positions of the patient's teeth. Preferably, the initialdeterminations of the final treatment positions of the teeth are madefrom the 3-D digital model, including particularly tooth shape and jawshape data, from the prescription information 27 from the orthodontist14, from the other information 16 from the orthodontist 14, and fromselections made by the operator 28 which aids the computer 30 b ininterpreting and simplifying the data for processing. The toothtreatment position calculations made in the design computer 30 b useprograms containing algorithms such as those described in the relatedpatents and applications identified above and others described below.The computer 30 b may also utilize interactive methods by which anoperator 28 monitors, selects options, and modifies the calculation oftooth finish positions as well as appliance design.

The initial determinations of finish position produce a preciseprediction of the prescribed treatment, taking into account theprogrammed algorithms and the exact three-dimensional shapes of thetooth surfaces. This results in an ideal dental or clinical archform orother intermediate or final tooth arrangement in which a treatmentdigital model, in the form of three-dimensional computer images andnumerical data, is provided for review, revision or approval by theorthodontist 14. Such a digital model may or may not be in the form of amathematical archform model in which some equation or formula is used toarticulate an arcuate, that is a generally arch-shaped arrangement ofthe teeth. A digital model of a dental archform may be in the form ofdigital data from which the teeth can be represented or displayed intheir generally arch-shaped arrangement for human evaluation.Preferably, the data is in a form that is capable of computer analysis.An image of the proposed treatment result is communicated digitally tothe orthodontist 14 through a computer network or other data link 31connected between the design computer 30 b at the appliance designfacility 13 and an interactive computer terminal 32 at the office 11 ofthe orthodontist 14. The link 31 along with software in the computers 32and 30 b provide an interactive system through which the orthodontistcan manipulate the initial determinations of calculated treatmentpositions as well as the course of treatment in response to which thedesign computer 30 b recalculates the final treatment positions of theteeth and generates display data for further review, revision orapproval by the orthodontist 14.

Once the tooth treatment positions are approved by the orthodontist 14,the computer 30 b automatically designs the appliance under thesupervision of an operator 28. As a digital appliance design isproduced, the design information, which includes three-dimensionaldesign display and numerical design data, is provided over the link 31to the terminal 32 for interactive adjustment and ultimately approval bythe orthodontist 14.

When the appliance design has been approved by the orthodontist 18, theanalysis and design computer 30 b produces archive files 34 that arewritten with all of the relevant information of the analysis and thehistory and prescribed treatment of the patient 14. Calculatedinformation for the patient is stored in a patient data file 36. Fromthe calculations, the manufacturing computer 30 c produces machinereadable code 42 for operating digitally controlled manufacturingequipment 38 to produce the appliance 25. An instruction document orfile 37 may also be produced, either by the computer 30 b or thecomputer 30 c, of information to aid the orthodontist 14 in treating thepatient 14 with the custom appliance 25.

For manufacture of custom orthodontic appliances of the types mostcommonly used at the present time, the manufacturing equipment 38preferably includes an appliance bracket forming machine 39 whichproduces custom brackets for the appliance 25. Automated bracket makingcan be carried out by casting or molding of the brackets from molds madeby the automated machines, by cutting slots at calculated angles ormachining other features in preformed blanks, or by other automatedbracket making methods. The machine 39 may shape the surfaces ofpreformed bracket bases, providing a design option of torquing the teethby either the bracket slot or base, as may be best for various bracketmaterials. The equipment 38 may also include an appliance archwirebending machine or other type of wire forming machine 40 to producecustom shaped archwires for the appliance 25. The equipment 38 in mostpreferred embodiments includes a machine for forming components to aidin the installation of the appliance 25 by insuring that the applianceis located on the surfaces of the teeth when installed. In archwire andbracket type appliances, this includes a machine 41 for the making ofbracket placement jigs, which cuts or otherwise forms three-dimensionaltooth fitting recesses that prevent placement of the appliance on atooth in all but the correct location on the tooth.

While conventional bracket and archwire appliances are illustrated anddescribed, concepts described herein can be applied to other forms oforthodontic appliances. Where in the conventional appliance, individualbrackets make connections between the appliance and the patient's teethwhile archwires interconnect the teeth via the brackets to exert thetreating forces among the teeth, a single piece appliance in which aresilient arch shaped element both interfaces with the teeth and exertsforces among the teeth can be used according to certain aspects of theinvention. Similarly, the three-dimensional surfaces that may beprovided on placement jigs to locate the appliance on the patient'steeth may be located on parts of an appliance itself, such as on thebracket itself or on a single piece generally arch-shaped appliance, sothat the appliance is self-positioning or self-locating. Such a jig mayor may not remain attached to the appliance or may or may not remain onthe patient's teeth so as to facilitate initial or continued positioningof the appliance on the teeth.

A suitable 3-D scanner 33 is illustrated in FIG. 3 and includes a laserscanner assembly 43. The laser scanner 43 has two electrically steerablelaser source-sensor assemblies 44 and 45, each with a laser source ortransmitter 44 a,45 a, respectively, and a laser sensor or receiver 44b,45 b. The laser assembly 44 is a high speed low resolution scannerused to generate a low resolution image to serve as a control map forthe laser 45, which is a high resolution scanner that generates datathat forms the three-dimensional model 26 used for tooth finish positioncalculation and appliance design and manufacture. The low resolutionlaser of the laser assembly 44 may be, for example, a laser scanningunit of the type manufactured by Keyence of Japan model LK031, while thehigh resolution laser 45 may be, for example, a laser scanning unit ofthe type manufactured by Keyence of Japan model LK081. The lowresolution laser 44 is preferably set to produce three orthogonalcoordinate measurements of points at a density of about two (2) datapoints per linear millimeter in each of three dimensions, while the highresolution laser 45 is preferably set to produce three orthogonalcoordinate measurements of points at a density of about ten (10) datapoints per linear millimeter in each of three dimensions.

The input computer 30 a is connected to the laser unit 43 to control itsoperating parameters and to interpret, format and store the 3-D databeing generated. The computer 30 a also steers the lasers 44 and 45 andorients the respective lower and/or upper halves 21,23 of the physicalmodel 20. For scanning, the halves of the model 20 are individuallymounted in a holder or support 46, which is mounted to an inner yoke 47so as to rotate thereon on its axis under the control of a servo motor48 which is controlled by the input computer 30 a. Similarly, the inneryoke 47 is pivotally mounted to an outer yoke 49 to pivot on an axisthat is perpendicular to the axis of rotation of the holder 46 andlocated to approximately intersect the half of the model 20 that ismounted on the holder 46. This allows the model half to be oriented atany angle desired with respect to the laser scanner 43 so that directline-of-sight views of the model can be obtained by the lasers of allsurface areas of the model. The outer yoke 49 is controlled by a servomotor 50, which is also controlled by the input computer 30 a.

The outer yoke 50 is mounted to a carriage 51 that is movablehorizontally on a table 52 on two axes by servo motors 53,54,respectively, both of which are controlled by the input computer 30 a.The laser assembly 43 is also mounted on the table 52. The movablecarriage 51 allows for precise placement of the half of the model 20 inthe holder 46 at a distance from the laser 43 for optimal focusing andfor the optimal angle of incidence of the laser on the model half beingscanned. The yokes 47 and 49 and the carriage 51 are preferably made ofheavy metal castings and the table 52 is preferably made of heavygranite blocks supported on a solid foundation so that vibrations thatcan affect the precise scanning of the high resolution laser 45 are nottransmitted between the laser scanner 43 and the holder 46.

When the scanner 33 is operated, the operator 28 sets up the scannerparameters through a setup screen at the computer 30 a and initiates lowresolution scanning of the lower jaw model half 21. For the lowresolution scanning, the model 21 is placed on the holder 46 and theinner yoke 47 is oriented by computer controlled operation of the motor50 so that the low resolution laser 44 scans a top view of the model 21which is displayed on the monitor of computer 30 a as illustrated in theleft window 55 a of FIG. 3A. The computer then reorients the yoke 47 togenerate low resolution views of the labial and lingual sides of theteeth, by rotating the model 21 in the holder 46 on the inner yoke 47 bythe computer controlled operation of the motor 48. This produces lowresolution panoramic lingual views represented by the windows 55 b,55 c,respectively. The views 55 a, 55 b, 55 c are effectively two dimensiondisplays generated for the purpose of providing the operator 28 with away to define the location of the various teeth of the model 21 in thethree-dimensional space at the scanner 33.

Controls are provided at the top of the screens of the display of thecomputer 30 that are relevant to the operation being performed or thedata being viewed. These controls include a menu, for example, menu 55e, that expands or changes as different selections are enabled in thecourse of the setup as well as a control 55 f for selecting variousviews and command buttons 55 g for actuating various calculations orinitiating equipment functions.

At the terminal of the input computer 30 a, the operator 28 can use apointing device to select points on the computer screen to define theinner and outer boundaries 56 a and 56 b, respectively, of the lowerjaw, and lines 56 c separating the individual teeth, from the top view55 a, so that each tooth can be represented as a separatethree-dimensional object. The lines 56 c may be automatically displayedon the elevational views 55 b, 55 c, on which the operator 28 canfurther select points to define labial and lingual tooth-gum lines 56 dand 56 e, respectively. Once the boundaries 56 a-56 e are defined fromthe view screens 55 a-55 c, high resolution can be initiated with thehigh resolution laser 45. High resolution scanning uses the boundarylines 56 a-56 c to precisely aim the laser 45 and thereby minimize theamount of data generated. The laser 45 generates up to fifty or moresegmented high resolution images of different and overlapping areas ofthe model 21, a composite screen display of which is illustrated in FIG.3B. The data points are each defined by three orthogonal x, y, zcoordinates. The separate images are each stored in separate data files.Once the separate image data files are generated, the images can beknitted together by the use of conventional software available for thatpurpose to produce a single three-dimensional high resolution digitalmandibular model of the patient's lower jaw with the teeth of thepatient. Initially, this is possible for the teeth in their pretreatmentmalocclused positions. As tooth finish positions or other treatmentpositions are calculated, as described below, the composite images canbe displayed to show teeth in any of such positions. FIG. 3B is acomposite image of teeth in ideal positions. Standard software isavailable that includes various three-dimensional image processingprograms and data conversion files provided with available laserscanning devices, to produce image files in standard data formats. Themaxillary tooth model 23 is similarly produced.

When the three-dimensional low and high resolution data files have beenproduced and stored by the input computer 30 a with data of separatethree-dimensional shapes of each of the patient's teeth as well asvector data locating and orienting each tooth shape model in itsmalocclused pretreatment position relative to a reference that locatesthe teeth relative to each of the others, the files are ready forfurther processing in designing the patient's occlusion by calculatingor otherwise determine finish position and then designing a customappliance to move the teeth to positions dictated by a treatment plan.The data files are loaded into the computer 30, which may be a separateanalysis and design computer 30 b, which is programmed to produce, underthe interactive guidance of an operator 28, and interactive involvementof the orthodontist 14, a three-dimensional digital model of the teethof the patient in some proposed posttreatment position. In doing so, aninitial proposed treatment position is calculated by the computer 30 band presented for review by the orthodontist 14. This electronic model,once modified and approved, serves as the basis for the design of thecustom orthodontic appliance that moves the teeth to the positionsrepresented in the model.

In the analysis and design computer 30 b, the data are filtered orprocessed to extract the geometric characteristics from thethree-dimensional images that are to be used to calculate the finalpositions of the teeth and to design the appliance. The extractedinformation defines a simplified digital model of the teeth, andpreferably also includes parameters customarily used by the orthodontistto define or describe tooth position, such as torque, tip and rotationangles, and may also include X,Y,Z displacements from some referencepoint, plane or archform. Typically, the three-dimensional highresolution digital model is in the form of a 3-D bitmap or raster imagewhere the simplified model is in the form of a vector image file,overlay or layer of the bitmap or raster image.

The generation of the simplified data image is initiated by an operator28 of the analysis and design computer 30 b by selecting a menu option,for example that named “Create Setup”, which appears on the main menubar at the top of the screen when adequate data to calculate toothtreatment positions is available in the computer. The “Setup” is a termoften used to refer to the finish, target or posttreatment positions ofthe teeth that are the objectives of the treatment plan. Selecting the“Create Setup” option displays a screen 60, an example of which isillustrated in FIG. 4. The screen 60 is divided into a main menu 61,sets of option buttons 62, one associated with each of the items on themain menu 61, an archform window 63, which displays an occlusal planview of one of the mandibular or maxillary arches, a tooth icon bar 64which displays an icon in either occlusal or labial view of eachindividual tooth in the arch in the window 63, and a selected toothwindow 65, which displays an enlarged view of a selected one of theteeth of the arch shown in the window 63. In the CreateSetup mode, thecomputer 30 b steps through a series of procedures in which the shape ofthe patient's lower jaw is determined and characteristic geometricfeatures of the patient's teeth are extracted from the three-dimensionaldigital model. The procedures are capable of being performed eitherautomatically with the computer 30 b making decisions, or interactivelywith an operator 28 and the program of the computer 30 b contributing todecisions. The procedures are explained in the interactive orsemi-manual mode for simplicity, but the decision making processes thatare explained can be made automatically using coding the described stepsin programmed algorithms.

The Setup mode starts with the setup of the teeth of the mandibulararch. As the Setup mode steps through its procedures, the number ofitems on the main menu bar 61 increases or otherwise changes so that theoperator can select from among all current available procedures orreturn to view the data displays that can be generated from dataproduced by completed procedures. This facilitates the entry of data inthe proper sequence. An initial procedure of the mandibular setup is thedefining of the mandibular arch in the form of a generally arch-shapedmathematical function that represents the centerline of the trough inthe patient's lower jaw bone containing the roots of the mandibularteeth. This function is provided to satisfy the first condition of theproposed tooth finish position calculation: that the patient'smandibular teeth should be contained and aligned within the cancellousportion of the patient's mandibular bone. The function can be considereda mathematical representation of the patient's mandibular skeletalarchform.

To generate a function defining the mandibular skeletal archform, anocclusal view 66 is displayed in the window 63 of the patient'smandibular arch from the high resolution digital model, as illustratedin FIG. 4A, from which an outline of tissue covering the mandibular bonestructure defining the mandibular trough MT is visible. The digitalbitmap image 66 is overlaid with a computer generated positioning gridG. The computer 30 b may pause at this point to allow the operator 28 toadjust the position of the grid G. The grid lines intersect theboundaries of the mandibular trough. These boundaries B_(B) and B_(L)can be selected by pattern recognition software, manually by theoperator 28 clicking with a pointing device at the grid and boundaryintersection points, or first with software and then allowing theoperator 28 to confirm or modify the software selections. The selectiondefines three-dimensional Cartesian coordinates La_(X,Y,Z) andLi_(X,Y,Z) of labial and lingual limits, respectively, of the corticalbone of the patient on both sides of the jaw, the data of which includea third Z dimension, derived from the three-dimensional model, of eachpoint that is selected on the two dimensional display. Once theintersection points of the mandibular trough boundaries and the grid aredefined, the computer 30 b calculates midpoint coordinates MP_(X,Y,Z)between each of the individual labio-lingual pairs of La and Li. Alsocalculated are the bone width distances DLL between each of therespective labio-lingual pair La and Li. The midpoints MP_(X,Y,Z) one ofwhich is the designated origin MP_(0,0,0) at the midpoint of the jaw,lie on an arch that describes the size and shape of the center of thecancellous portion of the mandibular bone. From this a mandibular troughequation MTE is derived, from which a symmetrical equation SMT may bederived.

Then, additional procedures are carried out, first for the mandibularteeth then for the maxillary teeth. These include refining theboundaries of each of the teeth from the archform images so that theirimages can be independently moved in the computer, selecting the widthsof the teeth across the teeth from their points of contact with adjacentteeth on the same arch, selecting landmarks or tooth prominences,including incisal edges, cusps, grooves and ridges, and defining thecrown long axes of the teeth, all in three dimensions. All of theseprocedures can be carried out using pattern recognition programmingtechniques. The accuracy of each procedure will benefit by allowingmanual confirmation or correction of computer selected parameters andlandmarks by an operator 28.

The teeth are identified with selection of menu tab 61 a (FIG. 4),either automatically, or by operator selection. The tooth identificationprocedure tells the computer, or confirms for the computer, adetermination made by an operator or the computer that a particularportion of the three-dimensional data represents the shape of aparticular tooth. Tooth identification can proceed, automatically by thecomputer 30 b and/or manually by the operator 28. For example, theselection can be made with a selection by the operator 28 of areas ofthe image in window 63 as the names of the individual teeth aresequentially displayed in a box 62 a, or by the operator confirmingimages sequentially displayed in the window 65 as corresponding to thetooth names displayed in the box 62 a as shown in FIG. 4B, or by theprogram in the computer 30 b making the determination for each of theteeth. Whether to make manual selections or to view automatedselections, the operator 28 can choose windows 64 or 65 to displayocclusal views or facial views of the individual teeth by clicking onbuttons 62 b or 62 c.

Next, the distances between the mesio-distal extremities, ormesio-distal widths MD TV, of each of the mandibular teeth are definedwith selection of menu tab 61 b. This width is the distance between thecontact points which a tooth will have with adjacent teeth when theteeth are arranged in contact with each other in a dental arch in theirtreated or finish positions. In addition, the sum of the mesio-distalwidths of the teeth on a dental arch constitutes the total length of thedental arch. The widths, once determined, are added together todetermine the total length of the dental arch and the amount of spaceneeded if all of the teeth at their original dimensions of the patientare to be retained. The mesio-distal widths can be determined eitherautomatically by software using algorithms to recognize and interpretthe teeth from the three-dimensional data and interpreting the mesialand distal contact points of the teeth with adjacent teeth, by theoperator 28 manually selecting the tooth intersection points on occlusalviews of the teeth as they are displayed in the window 65, or by theoperator confirming selections made by the computer. For simplicity, theMDWs are illustrated with respect to the mandibular teeth in FIG. 4A,and the determination of these widths is carried out, for mandibular andmaxillary teeth, using screens as illustrated in FIG. 4B for themaxillary teeth with the top view of the tooth selected for display inwindow 65.

More particularly, for both upper and lower teeth, MDWs may beinteractively picked by the operator from the enlarged occlusal image 65illustrated in FIG. 4B. With the MDW menu tab 61 b selected formandibular teeth, only occlusal views are available in the tooth iconbar 64 and for the enlarged individual tooth image window 65. Theoperator picks the mesial and distal contact points M_(X,Y,Z) D_(X,Y,Z),respectively, for the tooth, which in the illustration is the upper leftfirst molar. The points are selected by the operator by clicking apointing device at a point in the X,Y plane as displayed in the window65, whereupon the Z coordinate is determined from the high resolutiondata file image of the tooth. The computer 30 b calculates the distancebetween these points and stores the X, Y component of this width, fromthe coordinates of contact points M_(X,Y) D_(X,Y), as the MDW for thetooth. This width is defined in the data as a line in vector form in away that is related to its location in relation to the three-dimensionaldata of the shape of the tooth.

In the Setup mode, the operator 28 visually selects points that locatethe prominences of each of the teeth that serve as the landmarks thatform the starting points for the calculations of tooth ideal or finishposition calculations. In tooth position calculations, the computer 30 bmay use the selections directly, or may take into account actualthree-dimensional data of the tooth surfaces so that the accuracy of themanual selection of the landmarks is not critical. In lieu of manuallocation of the landmark points and all other selections, the locationsof the points may be done automatically by the computer through analysisof the three-dimensional tooth shape data of each tooth as well as ofthe adjacent teeth. Automatic selection may be presented for acceptanceor change by the operator 28. This may be particularly useful in thecase of teeth that are worn or damaged. Automatic selection seeks tolocate the selected points with the same objectives as those describedherein as done manually by an operator. The prominence landmarksselected in this way include the incisal center points of each of theanterior teeth, each of the cusps on the posterior teeth and each of themarginal ridges and central grooves on the posterior teeth, and each forboth the upper and lower teeth. When manually selected, these selectionsare made from the occlusal view of the teeth displayed in the individualtooth image window 65 as illustrated in FIG. 4B and can be adjusted froma front view as illustrated in window 65 in FIG. 4 or in a mesial distalview as illustrated in FIG. 4C.

The operator 28 also selects points to define a crown long axis CLA ofeach tooth, which is most easily done in the first instance in amesial-distal view, as illustrated in FIG. 4C. Definition of a crownlong axis for a tooth can be achieved manually by the operator 28selecting points to define a long axis plane LAP through the tooth. Thisselection is carried out, for example, by selecting two points on thefacial view to define an orientation of a line in the long axis planeproximate the facial side of the tooth, and two points on the occlusalview of the tooth to define an orientation of a line in the long axisplane proximate the occlusal surface of the tooth. Usually, such pointsare the major prominences such as incisal center points or mesial buccalcusps and central tooth gum intersection points.

Preferably, the selection of points to define the plane LAP is madefirst by selecting a labial and lingual point from the plan or occlusalview of the tooth, as illustrated for example in the individual toothimage window 65 in FIG. 4B. Then with such an LAP plane defined, amesial-distal view of the LAP plane as illustrated in FIG. 4C isdisplayed. From this view, gingival intersection points on the lingualand facial sides of the tooth can be selected, the midpoint of which,when calculated, defines a gingival center point GCP on the crown longaxis of the tooth. The CLA is calculated to extend through this pointthrough a predetermined one of the prominences of the tooth, dependingon the type of tooth involved. When all of the selections have beenmade, the digital model of the teeth includes two types of files, onecontaining the high resolution, three-dimensional digital tooth shapedata of each of the teeth arranged in their pretreatment positions andthe other containing simplified vector data representations of theteeth, each formed of a long axis plane LAP with the crown long axis CLAlocated therein, and with the tooth's mesial distal width vector MDW andthe various tooth landmarks of the tooth located in reference to theplane and the CLA. The torque and tip angles of each of the teeth can becalculated in reference to the orientation of the CLA relative to theocclusal plane or the plane of the MTE, and the rotation angle can becalculated from the orientation of the MDW about the CLA relative to thetangent of the MTE.

To assist the orthodontist, a perspective view showing each of the teethin their pretreatment positions is generated, as illustrated in FIG. 5.This view shows the three-dimensional solid shapes 70, produced fromhigh resolution, three-dimensional data from the raster image file, ofeach of the teeth of both the upper and lower dental arches arranged intheir pretreatment positions relative to each other. Each tooth is,preferably, illustrated in a different color. Three-dimensionalinformation can be displayed in several ways, one being by the use ofbrightness variations to represent the dimension perpendicular to thescreen, or by shadow shading, or both. Stereoscopic techniques may alsobe made to produce three-dimensional viewing, for example, using colorseparation and goggles for the user. Holography can also be used for thethree-dimensional displays. In the screen displays illustrated,superimposed on the solid images of the teeth are data from thesimplified vector image file, showing the long axis planes LAP, thecrown long axes CLA, and the grid G containing the equation of themandibular trough MTE. A user can toggle between the view of FIG. 5 andthe screen of FIG. 5A. which displays right, left and front views, aswell as occlusal views of each of the arches, in separate view windows71-75, along with a table 76 listing values for the torque, tip androtation angles of each tooth.

The Setup mode ends with the tooth treatment position determination, orSetup Calculation. In this phase, suggested tooth finish positions arecalculated and communicated to the orthodontist to adjust and approveprior to the design of the appliance, and then recalculated inaccordance with the interactive communications between the orthodontist14 at the office 11 and the design computer 30 b at the appliancemanufacturing facility 13. On the screen illustrated in FIG. 5A, anoperator or the orthodontist can select a Create Setup button 77 andcause the computer 30 b to calculate tooth finish or posttreatmentpositions, which can all be displayed together in a perspective view asillustrated in FIG. 5B, which is similar to FIG. 5, or as separateelevational or occlusal views as illustrated in FIG. 5C, which issimilar to FIG. 5A, in which the values of the calculated posttreatmentangles are numerically displayed in the table 76.

Tooth finish positions may be calculated by the methods described in therelated patents and applications identified above, for example, in U.S.Patent No. 5,431,562, to which are added the three-dimensionalcapabilities described herein. The calculations may take into accountskeletal, maxillary and mandibular criteria, including occlusion, indetermining the treatment positions of the teeth. In the calculations,the mandibular teeth, which should be contained and aligned within thecancellous portion of the mandibular bone are translated horizontally sothat their crown long axes are initially placed on the mandibular troughequation MTE. The buccal cusps and incisal tips of the mandibular teethare made to align incisogingivally to produce a substantially flatmandibular occlusal plane, and are arranged in a smooth archform inwhich the buccal cusps align buccolingually with the central grooves ofthe maxillary teeth. The marginal ridges of the maxillary posteriorteeth are arranged on the archform as the centric stops for the buccalcusps of the mandibular teeth. The central grooves of the maxillaryposterior teeth define buccal lingual locations of the centric stops ofthe mandibular teeth. The calculations are all carried out in threedimensions.

The calculations of final treatment positions includes calculation ofthe positions of the teeth in three-dimensional coordinates as well asthree orientation angles. The angles calculated are the torque angle orinclination, the tip angle or angulation, and the rotation angle. Thetorque angle is the angle of the tooth relative to the vertical in thefacial-lingual/vertical plane, with the vertical direction beingessentially that direction perpendicular to the occlusal plane. The tipangle is the angle relative to the vertical in a mesial distal/verticalplane. The rotation angle is the angle of the defined plane LAP with afacial-lingual line about a vertical axis. Initial rotation anglecalculations of the posterior teeth orient the teeth so that a line fromthe mesial-buccal cusp to the distal marginal ridge of the tooth ismesial-distal, that is, is parallel to the archform equation.Calculation of tip angle takes into account accepted norms and anyprescription by the orthodontist as well as adjustments to best fit thethree-dimensional surfaces and landmarks of occluding teeth at theocclusion while fitting the teeth with each other in their respectivearches and supporting bone.

In viewing the calculated finish positions, a user may view perspectivedisplays of the teeth of a single arch, as in FIG. 5D which shows boththe high resolution 3D data and the simplified vector data. The 3D solidimages and the simplified vector representations of the teeth may beviewed separately or together. In the vector data file, variouslandmarks may also be displayed, as, for example, in FIG. 5E where theincisal tips 78 and buccal cusps 79 of the lower teeth are illustrated,which landmarks may serve, for example, as the reference points on theteeth for aligning the lower teeth on a best fit equation for the lowerarch, such as the best fit buccal cusp equation BFBCE that is describedmore fully in the related patents.

In viewing the calculated finish positions that are suggested by thecomputer 30 b, the orthodontist 14 can adjust the positions of any ofthe teeth in six degrees of freedom on a computer at the orthodontist'soffice 11 which is connected to the computer 30 b at the appliancedesign facility 13 through a telephone or wireless link or othernetwork. Normally, an orthodontist first considers adjustments to thetorque, tip and rotation angles of the teeth. The angle adjustments aremade by selecting the angle and tooth to adjust in the table 76 (FIG.5C) and then to adjust a slide control 76 a or type in a new value forthe angle to be adjusted. As the value changes, the display changes toreflect the change in the value being made. The orthodontist can alsoadjust any tooth in x,y,z coordinates or in gingival-occlusal,facial-lingual and mesial distal coordinates. Rather than translatingthe entire tooth, which presents interference issues, the orthodontistmight adjust particular landmarks. When the adjustments have been madeby an orthodontist and a testing of the changes made is desired, theorthodontist selects the Calculate Setup button 77 to cause the computer30 b at the appliance design facility to recalculate the treatmentpositions of all of the teeth based on the changes made by theorthodontist. In doing so, the orthodontist can select or unselect, incheck boxes 77 a provided, the parameters that can be changed in thesetup calculation. In this way, the orthodontist can also testextractions by selecting the elimination of selected teeth from thecalculations, and may test over-corrections that the orthodontist mightdesire. The setup recalculations proceed according to the orthodontistsselections to position the teeth in stable positions according topredetermined criteria stored in the computer 30 b.

When the tooth finish positions have been finally calculated followingthe iterations between the computer 30 b and the orthodontist, theorthodontist communicates satisfaction with the treatment positions tothe appliance design facility 13 and the operator thereat then commandsthe computer 30 b, or the computer can be respond automatically, todesign the appliance. In designing an appliance according toconventional straight-wire orthodontic appliance techniques, theappliance will be one made up of brackets to be bonded to the patient'steeth which support an interconnecting archwire. The straight wireappliance design proceeds with the design of an archwire, the design ofbrackets and the design of bracket placement jigs, all custom to thetreatment plan approved by the orthodontist for the specific patient.The design of archwires can be carried out in accordance with thepatents incorporated above, such as U.S. Pat. Nos. 5,454,717 and5,447,432. Archwire designing concepts such as those discussed in U.S.Pat. No. 5,474,448, hereby expressly incorporated by reference herein,are also particularly suitable. Archwire design places an archwire 80 atan optimal low profile position relative to each of the teeth, asillustrated in FIG. 5E for the mandibular arch. The archwire 80 isdesigned to lie in an archwire plane A WP through the teeth when theteeth are in their posttreatment or finish positions, as illustrated inFIG. 5F for a mandibular first bicuspid. Once the archwire 80 has beendesigned, brackets 81 are automatically designed by the computer 30 b toform the connection between the archwire 80 and the patient's tooth,with the shape of the custom archwire 80 defining an archwire slot 82 inthe bracket 81 and the three-dimensional data from the 3-D highresolution data file for the tooth defining the contour of the bracketmounting base 83. To facilitate the proper identification of thebrackets to the teeth on which they belong, these bracket mounting basesare preferably shaped in accordance with the concepts described in U.S.Patent No. 5,993,206, hereby expressly incorporated by reference herein,with the bases thereof being scaled reductions of the profiles of thecrowns of the teeth viewed from the facial side.

The screen of FIG. 5E illustrates an automatically designed appliance onthree-dimensional solid images of the mandibular teeth, shown in afacial view screen window 84 and an occlusal view window 85. With thisscreen, a user can select the individual teeth to display in anindividual tooth window 86, and can also display the cross-sectionalview of the tooth as illustrated in FIG. 5F. The appliance formed of thearchwire 80 and brackets 81 is illustrated on vector images of the teethin a perspective view in FIG. 5G, which can also be selected by a userfor display. As with the positioning of the teeth, the design of theappliance can be adjusted by a used, who may be either the operator 28at the appliance design facility 13 or the orthodontist 14 on a computerat the office 11. In particular, the orthodontist can adjust the torque,tip and rotation of the brackets just as these parameters of the toothwere adjusted in arriving at the tooth finish positions, so as to changethe relationship of the archwire slot relative to the tooth. The bracketlocation on the surface of the tooth can also be adjusted by theorthodontist. Similarly, the archwire can be reshaped. When thesechanges to the appliance have been made by the orthodontist, theappliance design may be recalculated. In addition, the tooth treatmentor finish positions can be recalculated and the recalculated positionsdisplayed to show the effects, if any, that changes to the appliancedesign would cause to the relocations of the teeth when treated withsuch an appliance.

Once the archwire 80 and brackets 81 have been designed and thepositions of the brackets on the teeth determined, jigs 87 areautomatically designed by the computer 30 b. From bracket design andpositioning information and from the high resolution, three-dimensionaldata of the shape of the teeth, the jigs 87 are designed so that theyfit at a unique location and orientation on the occlusal surface of thecrown of one of the teeth 92 so that the corresponding custom bracket 81for that tooth is precisely supported at its calculated placementposition on the tooth 92 during the bonding of the bracket 81 to thetooth with adhesive by the orthodontist. FIG. 6 illustrates such a jig87 as a solid three-dimensional object, dimensioned and positioned tointersect the one of the teeth 92 on which a bracket 81 is to be placed.The bracket is shaped and placed so as to avoid interference withadjacent teeth in either their pretreatment or posttreatment positionsand during the movement of the tooth during treatment.

In particular, the body of the jig 87 is designed to have a cavity 88 onone side thereof to fit precisely against the occlusal surface 91 ofone, and only one, of the patient's teeth 92. The surface of the cavity88 has a shape defined by the high resolution, three-dimensional data ofthe occlusal surface 91 of the tooth over which the jig 87 is to fit.The jig 87 has a bracket engaging element 89 configured to removablyconnect to a bracket 81, which has a hole 90 in the archwire support 94thereof to receive the element 89. The element 89 is in the form of acylindrical post having a shoulder thereon to fix the spacing of thebracket from the jig. When assembled for shipment to the orthodontist,the element 89 is lightly bonded to the bracket with wax or adhesive.When the jig 87 is fit on the crown of the tooth, the bracket 81 ispositioned and oriented in one, and only one, way on the tooth becausethe bracket 81, and particularly the archwire slot 82 thereof, is in aspecific design position and orientation relative to the surface of thecavity 88 when the jig and bracket assembly are placed on the tooth.When the jig 87 is so positioned on the crown of a tooth with the cavity88 conforming exactly to the occlusal surface of the tooth, the base 83of the bracket 81 is supported in a predetermined position on the toothaccording to the automated custom appliance design. When bonded withadhesive in this position on the tooth, the archwire slot 82 of thebracket 81 will be located at its design position and orientationrelative to the occlusal surface 91 of the tooth 92.

The design of the custom orthodontic appliance produces data files 36from which automatic manufacturing equipment can be controlled toproduce archwires and brackets and the jigs for installation of thebrackets at design locations on the patient's teeth, or otherappliances. Most archwires, such as those made of stainless steel, canbe made on wire bending machines controlled by signals that representthe wire as a curvature that is a function of the wire length from endto end. Such a wire bender is described, for example, in U.S. Pat. No.5,447,432. Wires are sometimes desired that are highly elastic andformed of materials such as titanium alloys that cannot be easily oraccurately formed by bending. Such wires can be formed on equipment suchas the wire forming system of the type illustrated in FIG. 7.

The system 110 of FIG. 7 uses a mill 11 to form a cut 113 that is theshape of an archwire as it appears in the archwire plane AWP through asheet 112 of metal, ceramic, machinable rigid foam or other temperatureresistant material that is about 0.01 inch thick. The cut 113 that isthe shape of the archwire separates the sheet 112 into two parts, 112 a,112 b, which are inserted into opposite ends of a slot 114 which isformed in a ceramic block 115. The block 115 is formed of two parts 115a,115 b that are pinned together to define the slot 114 between them. Ablank length of archwire material 116 is inserted into the slot 114between the halves 115 a,115 b of the block 115. Then, the two parts 112a,112 b of the sheet 112 are inserted into the slot 114, and broughttogether on opposite sides of the wire 116, so as to clamp the wireblank 116 between the sheet halves 112 a, 112 b in a groove that is theshape of the cut 113 of the custom archwire 80, described above. Theblock 115 is then heated until the wire blank 116 is annealed andpermanently assumes the shape of the cut 113. The block 115 and sheethalves 112 a,112 b are then separated and the wire 116 that is formed inthe shape of the custom archwire 80 is removed.

The automatic formation of custom brackets is accomplished by one ofseveral systems, one being that described in U.S. Pat. No. 5,454,717, inwhich individual bracket blanks are mounted in separate fixtures on theworkpiece holder of a mill and the slots are cut at custom locations andorientations in the archwire support of the bracket, which is thenwelded to a bonding base that is preformed to a standard curvature of atooth. One alternative bracket manufacturing system that uses baseshaving standardized curvatures is the system 120 illustrated in FIGS.8A-8D. The system 120 uses a die assembly 123 which has a plurality ofrecesses 121 therein, each having a curvature conforming to the standardor statistically average curvature of a respective one of a patient'steeth at the point on the facial side (or lingual side in the case oflingual appliances) of the crown at which an orthodontic bracket istypically attached. A single sheet 122 of deformable metal material of atype and thickness out of which bracket bonding bases 83 a can be formedis placed into the die assembly 123, and the sheet 122 is deformed suchthat a portion of it conforms to each of a plurality of cavities orrecesses 121, one cavity for each bracket of a set. The force to deformthe sheet 122 may be applied directly against the sheet 122 by staticfluid pressure, preferably, using a liquid such as an oil.

When the sheet 122 has been deformed, a layer of wire mesh 124 is weldedto the side thereof that includes the usually concave sides of thebracket bonding bases 83 a. On the opposite and usually convex side ofeach of the bases 83 a is welded a blank archwire support 94 a of anorthodontic bracket. Then, the sheet 122 with each of the archwiresupports 94 a welded thereto is mounted on a slot cutting mill 125,which cuts the slots in all of the archwire supports 83 a of all of thebrackets. Each of the bases are then cut from the sheet 122 using alaser cutter or some other cutter that is, preferably, computercontrolled.

Another alternative system for automatically forming custom brackets isthe system 130 illustrated in FIGS. 9A-9C. In the system 130, custombrackets 83 b are formed in layers, for example, by jet printing ofmaterial to build up the bracket in layers by a stereo-lithographyprocess. The printing of the material can be by directly depositingmaterial of which the brackets are made to thereby form the bracket orto deposit wax or other pattern material to form a pattern from which amold can be made to cast the bracket, such as by an investment castingmethod. In one such version of the system 130, a print head 131 is setup to jet print two types of wax, one which will either be melted ordissolved away, which is deposited on the portions of each layer thatare external to the bracket being formed, and the other type of wax,which is deposited on portions interior to the bracket being formed,which will remain. An object 133 that is printed with such a method iseither heated or chemically treated so as to remove the wax that isexternal to the bracket, leaving only the wax internal to the bracket,which is now a pattern in the shape of the bracket to be formed. The waxwhich becomes the pattern, may, for example, be of a higher meltingpoint than the other wax or may be of a type that is insoluble in asolvent that will dissolve the other wax. The waxes are deposited inuniform layers, with the wax that is to form the pattern being depositedin the shape of a cross section or slice of the bracket and the otherwax occupying the other areas of the layer that are to be removed. Thelayer is thereby deposited as a uniform thickness of the two waxes, withthe pattern cross section defined by the one wax and the area around thepattern defined by the other. The wax around the pattern may, therefore,be selectively melted or dissolved away, leaving only a wax pattern inthe shape of the appliance to be molded.

With such a system, the object may include a set of custom brackets 83 bmade according to the design method described above, interconnected by astem 134, formed in a mold made from a pattern 135 formed out of the waxtype that will remain after treatment, which can form the wax patternfor use in an otherwise conventional investment casting method ofmanufacture of the brackets. With such a method, the wax pattern made ofthe remaining wax is set in plaster or some other medium and theremaining wax is either burned out or evaporated. Then metal is injectedinto the mold cavity forming the custom brackets 83 b. Brackets 83 bmade by this method can have not only custom located archwire slots butwill have custom curved bases formed to precisely match the curvature ofthe teeth from the high resolution, three-dimensional data thereof. Byprinting in layers, the layers can be of the same approximate thicknessas the resolution of the dots of wax being printed, thereby providingthe same resolution in the direction perpendicular to the layers asexists in the planes of the layers.

Use of printing techniques to produce brackets, preferably layer bylayer, is capable of producing brackets and other appliances orappliance components having full three-dimensional properties. Thismethod is particularly useful for brackets made of materials such asplastic or ceramic that are not as easily machined, which can then bemolded in molds made by this process. With such brackets, the bases canbe shaped to conform precisely to the three-dimensional curvature of thesurface of the tooth at the ideal placement position for the bracket onthe tooth. Torque of the bracket can be built into the base of thebracket rather than being built into the archwire slot by controllingthe angle of the slot.

Brackets can be made according to the system 130 by printing thematerial of which the bracket is to be made, such as metal, plastic orceramic, rather than printing a material of which a pattern is made,such as wax. This direct stereo lithographic printing eliminates theneed to cast a custom mold for the appliance around a pattern, theninjecting the mold with appliance forming material to form theappliance. Methods of manufacture are known or are evolving by whichmaterials, such as, for example, metal or ceramic, can be provided inpowder form mixed with a binder. Such a material could then be depositedin a layer in the shape of the cross section of an appliance, with thearea around the shape being formed only of a binder like material. Thedeposition may be by printing. Like the pattern printed for theinvestment casting method, the binder can be removed by heat or solvent,leaving a bracket or other appliance or appliance pail formed of thematerial in the three-dimensional shape of the orthodontic appliance.Instead of making a mold of the material, after all layers have beenapplied to produce the three-dimensional appliance, the material, whichis metal, ceramic or other material, and which is relatively fragilewith the binder removed, is then heated to just below its melting point,and sintered until it achieves the desired cohesion and density. Suchsintering usually results in shrinkage which must be accounted for byenlarging the shape of the appliance cross sections being printed by ascale that compensates for the predicted shrinkage.

Other techniques for producing the appliance in layers may be used, witheach layer being controlled by the manufacturing computer 30 c toconform to the shape of the custom appliance design. Materials may, forexample, be deposited in uniform layers, with a cross section of theappliance then being bonded, such as for example, being sintered withthe use of a computer controlled laser, for example, in the shape of thecustom appliance design. After all of the layers have been applied, thematerial which has not been so bonded is removed leaving athree-dimensional appliance. The laser, or other energy source,photographically exposes the material in a way similar to that used inpatterning photo-resist film in the manufacture of semiconductors,thereby fixing the material so that it can be selectively removed toproduce a bracket shaped object.

Brackets may be configured with surfaces on them that facilitate theirpositioning on a patient's teeth using separate jigs or a separatesurface on the bracket in lieu of jigs. In the bracket illustrated inFIG. 6. for example, the vertical hole 90 is formed in the arch wiresupport for the removable connection thereto of a post-like element 89of a jig 87. The manufacture of the jigs for positioning such bracketsmay be carried out with any of several manufacturing techniques thatwill reproduce the precise shape of the tooth crown occlusal surface 91in the jig 83, so that the jig will fit in one, and only one, positionand orientation on the crown of the tooth of the patient to which acustom appliance is to be bonded. A suitable method to make such a jigis to machine the cavity 88 of the jig 87 out of a rigid foam materialusing a precision computer controlled mill sized and configured for thatpurpose. One such material is LAST-A-FOAM type FR3720 manufactured byGeneral Plastics Mfg. Co. of Tacoma Washington. Preferably, a set of allof the jigs required to neat a particular patient is formed of a singleintegral block 98 of the foam material, as illustrated in FIG. 6A. Theblock thereby facilitates the holding of the jigs for machining. Achannel 99 may be cut by the mill around each jig so that by simplyslicing the upper surface of the foam from the block of foam, theindividual jigs may be separated. The crown surface cavities 88 are cutinto the jigs 87 in accordance with the three-dimensional data from thehigh resolution 3-D data file, as illustrated in FIG. 6B. The portion ofthe data used to define the shape is determined in the appliance designprocess wherein the bracket placement positions on the patient's teethare calculated.

What is described above includes the preferred embodiments of theinvention. Those skilled in the art will appreciate that additions toand modifications of the system and method of the invention, and thedetailed manifestations thereof, may be made without departing from theprinciples of the in inventive concepts set forth herein.

1. A method of manufacturing an orthodontic appliance comprising:producing digital data defining a three-dimensional surface of anorthodontic appliance; manufacturing the orthodontic appliance based onthe digital data, by a process that includes depositing material, inaccordance with the digital data, layer by layer in a plurality oflayers each constituting a two-dimensional cross section of a solidobject having an edge defined by data of the three-dimensional surface,the layers being stacked in a third dimension to form the solid objecthaving a three-dimensional surface defined by the data; the solid objecthaving the three-dimensional surface is an orthodontic appliance havinga surface defined by the three-dimensional surface of the object.
 2. Amethod of manufacturing an orthodontic appliance comprising: producingdigital data defining a three-dimensional surface of an orthodonticappliance; manufacturing the orthodontic appliance based on the digitaldata by a process that includes depositing material, in accordance withthe digital data, layer by layer in a plurality of layers eachconstituting a two-dimensional cross section of a solid object having anedge defined by data of the three-dimensional surface, the layers beingstacked in a third dimension to form the solid object having athree-dimensional surface defined by the data; the material beingselectively formed in each layer of a first portion of material that isremovable chemically, thermally or mechanically and a second portion ofmaterial that remains after removal of the first portion to form apattern having the three-dimension surface thereon in the shape of acustom orthodontic appliance or component thereof; the materialincluding wax of at least two types, one forming said first portion andone forming said second portion, and the deposition thereof toselectively form the layers including the selective depositing of theportions of material in layers to define a cross section of the objectwith said second portion forming the pattern and being at leastpartially surrounded by a removable medium formed of said first portion;and the manufacturing of the orthodontic appliance including removingsaid first portion to form the pattern of the second portion and usingthe pattern in a manufacturing step to impart the shape to theorthodontic appliance, thereby producing the orthodontic appliancehaving a shape defined by the data.
 3. The method of claim 1 wherein:the appliance is an orthodontic bracket.